Structure Shielding Against Initial Radiations from Nuclear Explosions. I. Attenuation of Air Secondary and Fission Product Gamma Rays

Calculations and resulting data are described which are intended for use in estimating the protection afforded by buildings against nuclear radiations emitted from a nuclear burst in the first half minute or so. The basic source configuration is that for which one assumes equal likelihood of the explosion occurring on a ring of elevation 30 deg above the horizontal, relative to a structure location on the ring axis. Source spectra and angular distributions corresponding to large distance (≳1 mile) from burst point to structure are used. As sources we discuss here only gamma rays from fission products and from neutron interactions with air molecules.